To be clear, QMT sells you a 3 phase mill and a VFD, not one installed or how too instructions. You need to get additional parts, switch gear, wiring, etc., install it yourself and program the VFD. Not too difficult, but it is not a turn key system. There are also factors such as adding a power drawbar and other aspects that differ between the TS and TV models. The simplest is the single phase 935TV which would be plug and play, but the 3 phase 935TS should be more durable over the long hall, and a VFD has many nice features like soft start and braking. Long term single phase motors can have problems with their start/run capacitors in particular if started and stopped frequently.
On the DRO, the 3 axis ES-12B works very nicely with this mill. Installing it yourself saves some $$, and is a good learning experience, but it may take 2-3 days to figure it out.
The power feed (PF) for the X-axis is easily installed, if you want to save a few bucks or just want to do it yourself. It is definitely worth having though, as it makes long(er) cuts along the X-axis so much easier (and better looking). If Matt will install the DRO for you, it would save a few headaches. And, if anything goes wrong it's on him.
If the head is like mine, changing speeds is not a big deal really. While I mostly leave mine in the middle of the range and use the speed pot on the VFD, it only takes a few seconds to loosen the motor, pivot it slightly, and slip the belt onto a different ratio. Because I very seldom do it, I have a harder time remembering how to change from hi to low range.
Of course you will be required to post copious amounts of pics if you buy this new mill...